1. Field of the Invention
The present invention relates to a data storage device and a data storage method for providing time certification of data stored.
2. Description of the Related Art
Conventionally, data processing devices, such as printers, facsimile devices, multi-function printers, copiers, digital cameras, and the like, have clocks built in. Time kept by the clock has been recorded on paper documents as the time at which data was created, or the time at which a job was processed (for example, Japanese Patent Laid-Open No. 06-078144).
Alternatively, a clock has been built into data processing devices such as printers, facsimile devices, multi-function printers, and the like, with time kept by the above-described clock being recorded as data of the time at which data was created, or the time at which a job was processed (for example, Japanese Patent Laid-Open No. 11-175273), and with the data, to which such time is appended, being stored in a data storage device.
However, the above-described conventional data processing devices have had the following problems. The time kept by the clock built into the above-described data processing device could be set by an administrator or user of the data processing device, and accordingly, setting the clock to a different time from the real time could not be prevented. In other words, the time at which data was created, or the time at which a job was processed, appended to paper documents, has not always been precise time.
Additionally, the time that is appended by the control software of a data processing device has not been dependable from the standpoint of a third party, and also the time information read out from the data storage device has not always been precise information.
Additionally, there has been the possibility of the data stored in the data storage device being modified or altered following time information being appended thereto.